The group I've been playing with has two or three songs that are in drop tunings and tuning during a live show is a pain. I have a second guitar, but one song is half-step, the other is whole step. The other guitarist in the band has a multi-effects pedal that has a built in function that allows him to drop down a half or whole step by clicking a button. Are there stand-alone pedals that do this (I've seen octave pedals, but the ones I have experience with aren't for half/whole step type things, they're variable and I don't have the ear to set that on the fly)? I don't really want to purchase a multi-effects pedal when I've already got a separate rig that does all that, so a stand-alone would be glorious.